This invention relates to a small recreational watercraft equipped with a jet water propulsion device in the aft portion of the bottom of the hull, which is designed to be maneuvered by an operator using a steering bar installed adjacent the fore portion of the hull.
This type of small watercraft is generally used for leisure sports and is designed to permit an operator to enjoy relatively rough operation, such as quick starts and sharp turns, while maintaining the balance of the craft by adjusting the position of the operator's body. Therefore, since the operator sits adjacent the aft portion of the hull in prior art crafts, the balance of weight in the longitudinal direction of the hull during travel has traditionally been given primary importance. The engine for driving the impellers of the water jet propulsion device has been mounted in the fore portion of the hull, as described in Japanese Pat. Provisional Pub. 61-244692 and U.S. Pat. 4,768,453 of Sept. 6, 1988, for example.
As shown in FIG. 7 of this application, the fore end of the hull of a conventional small watercraft 1' having an engine 10' mounted in the fore portion of the hull, is submerged or sinks below the water line (W.L.) while the aft end of the hull is kept afloat above the water line when no one is aboard. Usually the operator and any passenger mount the small watercraft from the aft end of the hull, and therefore if the aft end of the hull is afloat above the water as mentioned above, it is not easy to get aboard by climbing onto the craft from the water. Also, the difference in the trim (the posture of the craft in the water) between when the operator et al. are aboard and when not is conspicuous because the weight balance in the longitudinal direction of the hull changes greatly by the weight of the operator etc. mounting the aft portion.
Therefore, such a small watercraft cannot offer fully the enjoyment of easy planing operation partly because of the difficulty of getting onto the hull.
Furthermore, due to the relatively long distance between the engine and the water jet propulsion device, a long drive shaft is needed to transmit the driving force from the engine located in the fore portion to the impellers of the water jet propulsion device located in the aft portion. Also, some types of such watercraft require lengthy cooling water piping between the water jet propulsion device and the engine in order to cool the engine. The drive shaft and piping must therefore be long and the structure of the hull (particularly near the drive shaft) is complicated by the arrangement of these parts.
The primary object of this invention is to solve the above-mentioned problems by providing a small watercraft that is easy to board, has less variation in the trim when the operator et al. are on board and when not, that is easy to board from the aft portion, has good stability in the stationary state even when two persons are on board, has excellent acceleration to planing speed, can be easily operated regardless of operator skill, is comfortable to ride, has higher performance regarding sharp turns and quick starts than conventional watercraft, making it easier to enjoy planing, and making it possible to reduce the length of the power train, such as the drive shaft, thus simplifying its construction.